Shining the spotlight from the bow of our john boat, shining specks materialized across the inky black waters within the searching beams of light. Although invisible with the unaided eye, the glowing red eyes revealed dozens upon dozens of alligators in the lake surrounding our boat. By pursuing the glowing eyes, we were there to capture, tag and release as many gators as we could that night. It was on that 1995 trip our ecology professor taught us the details of the tapetum lucidum.
Many animals have a reflective membrane in the eyes called the tapetum lucidum, which aids in night vision. The crystals in this incredibly designed membrane take the low light coming in through the eye and reflect it, thereby multiplying the amount of light passing through the retina. Built-in night vision!
That same tapetum lucidum is what causes that annoying “red eye” in your indoor flash photographs of family and friends. But while in the Okefenokee, instead of spending post-production time on “red eye reduction,” I used it to my advantage. As a gator passed by at dusk, I set my camera for a decent nighttime exposure. And even though it was two far for my flash to fill the scene with light, I used just enough flash to cause intentional “red eye” on the alligator, thus producing an eerie, dragon-like appearance in the photograph.
iNaturalist observation: https://www.inaturalist.org/observations/29933513